Creates a GraphViz dot file for the specified app names based on their models.py.
You can pass multiple app names and they will all be combined into a single model.
Output is usually directed to a dot file.

Several options are available: grouping models, including inheritance,
excluding models and columns, and changing the layout when rendering to an output
image.

With the latest revisions it’s also possible to specify an output file if
pygraphviz is installed and render directly to an image or other supported
file-type.